This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A147658 #14 Feb 08 2022 23:26:23 %S A147658 1,3,2,-3,-4,3,6,-3,-8,3,10,-3,-12,3,14,-3,-16,3,18,-3,-20,3,22,-3, %T A147658 -24,3,26,-3,-28,3,30,-3,-32,3,34,-3,-36,3,38,-3,-40,3,42,-3,-44,3,46, %U A147658 -3,-48,3,50,-3,-52,3,54,-3,-56,3,58,-3,-60,3,62,-3,-64 %N A147658 (1, 2, -4, 6, -8, ...) interleaved with (3, -3, 3, -3, 3, ...). %C A147658 POLYMOTZKINT A147657 = [1,2,3,...]. %C A147658 POLYMOTZKINTINV operation on [1,3,5,7,...], such that POLYMOTZKINT A147658 = [1,3,5,7,...]. %C A147658 Cf. A005717 for an example of the POLYMOTZKINT operation. %H A147658 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,-2,0,-1). %F A147658 a(1) = 1; a(2*k) = (-1)^(k-1)*3; a(2*k+1) = (-1)^(k-1)*2*k for k >= 1. - _Georg Fischer_, Nov 02 2021 %p A147658 with(ListTools): Flatten([1, seq([(-1)^(k-1)*3, (-1)^(k-1)*2*k], k=1..32)]); # _Georg Fischer_, Nov 02 2021 %Y A147658 Cf. A005717, A147657. %K A147658 easy,sign %O A147658 1,2 %A A147658 _Gary W. Adamson_, Nov 09 2008 %E A147658 a(25) ff. corrected by _Georg Fischer_, Nov 02 2021